In the field of molecular nanoelectronics, few materials show as much promise as one-dimensional nanostructures, and in particular carbon nanotubes that comprise hollow cylinders of graphite that have a diameter of a few Angstroms. Nanotubes and other like one-dimensional nanostructures can be implemented in electronic devices, such as, for example, diodes and transistors, depending on the nanoparticles electrical characteristics. One-dimensional nanostructures are unique for their size, shape, and physical properties. For example, carbon-based nanotubes resemble a hexagonal lattice of carbon rolled into a cylinder.
Besides exhibiting intriguing quantum behaviors even at room temperature, carbon-based nanotubes exhibit at least two important characteristics, a nanotube can be either metallic or semiconducting depending on its chirality, i.e., conformational geometry. Metallic nanotubes can carry an extremely large current density with constant resistivity. Semiconducting nanotubes can be electrically switched “on” or “off” as field effect transistors (FETs). The two types may be covalently joined (sharing electrons). These characteristics point to nanotubes as excellent materials for making nanometer-sized semiconductor circuits. Similar properties exist for other one-dimensional nanostructures.
Carbon-based nanotubes and other like one-dimensional nanostructures are thus becoming strategically important for post-Si FET scaling. However, there is no known self-aligned process comparable to conventional CMOS technology. A self-aligned process for a CMOS device including one-dimensional nanostructures would provide a simpler sequence of processing steps as compared to a non-self-aligned process and it reduces processing error that typically occurs when a non-self-aligned process is used. Moreover, a self-aligned process provides a structure having reduced parasitics as compared to a non-self-aligned structure.
In view of the above, there is a need for providing a self-aligned process for fabricating a CMOS device that includes one-dimensional nanostructures, such as nanotubes and nanowires.